What is the function of the 1 k resistors on an Arduino Pro on the UART pins?
I have not yet actually experimented with the board to test it, but I’m guessing that their function is to prevent some serial peripheral device that is connected to the shield headers from loading down the UART too much and preventing communications and programming over the FTDI cable?
So, suppose for example, you plug in a shield that contains a XBee module or something like that connected to the UART. Usually with an Arduino, if you leave that plugged in, you can’t reprogram because it’s loading down the UART lines, and ordinary serial ports are not designed to have more than two devices on the bus, because the receivers cannot go tristate.
Do these resistors on the Arduino Pro prevent this problem?
If so, that’s really convenient and really clever, and it should be applied by the Arduino team to all the official Arduino hardware as well! 